Psy, the South Korean rapper whose viral pop hit “Gangnam Style” has been viewed more than 900 million times on YouTube, participated in two anti-American performances about a decade ago, a story that finally trickled into English-language media this week. Although the K-Pop star quickly issued a public apology, the controversy could build, as Psy is slated to perform Sunday night at “Christmas in Washington,” the annual holiday concert held at the National Building Museum, with President Obama and his family in attendance.

The concert is an annual charitable event benefiting Children’s National Medical Center, and it is a longstanding tradition for the president and first lady to attend. As of Friday evening, Psy was still scheduled to perform, according to a publicist for the program.

“Kill those f------ Yankees who have been torturing Iraqi captive / Kill those f------- Yankees who ordered them to torture / Kill their daughters, mothers, daughters-in-law, and fathers / Kill them all slowly and painfully,” Psy sang at a 2004 concert in South Korea, held in protest of the United States and its military. The lyrics are not his — the song, “Dear American,” is by South Korean metal band N.E.X.T. — but the performance is in stark contrast to the smiling, good-natured pop star that Americans have been introduced to over the past six months.

“Gangnam Style” recently became the most-viewed video in YouTube’s history, and the song — along with its silly accompanying “horse dance” — has been largely inescapable since it starting dominating the Internet this summer and eventually became the subject of countless pop culture parodies and references.

The performances that have gotten Psy — the 34-year-old whose real name is Park Jae-sang — in trouble come from a time when he, like others of his generation in South Korea, was caught up in a wave of anti-Americanism, driven by complicated cultural and political circumstances, including the Iraq War and a 2002 incident in which a U.S. military vehicle struck and killed two 14-year-old girls walking along the side of a road outside Seoul.

“The song I was featured in — eight years ago — was part of a deeply emotional reaction to the war in Iraq and the killing of two Korean schoolgirls that was part of the overall antiwar sentiment shared by others around the world at that time,” Psy said in a statement released Friday afternoon. “While I’m grateful for the freedom to express one’s self, I’ve learned there are limits to what language is appropriate and I’m deeply sorry for how these lyrics could be interpreted. I will forever be sorry for any pain I have caused by those words.”

The 2004 concert was the second incident in which Psy expressed anti-American views. Two years earlier, Psy — who attended Boston University and Berklee College of Music in the late ’90s — walked onstage at a performance that protested the large U.S. military presence in South Korea. He wore an outlandish, glittery red costume and gold face paint. As the crowd cheered him on, Psy lifted a large model of a U.S. tank and, to cheers and applause, smashed it against the stage.

A Gallup poll at the time found that 75 percent of 20-something Koreans said they disliked or hated Americans. Many charged that the United States was making South Korea its pawn. Psy’s 2002, gold-faced performance was, for all its shock value when seen in isolation, nothing atypical of the year’s backlash. More protests erupted in 2004 because of South Korea’s support of the Iraq War and the widely held view that America pulled the country into the conflict against its will.

But there were some deeper cultural forces at work, including South Korea’s Sunshine Policy, a pursuit of rapprochement with North Korea from 1998 to 2008 that put the country at odds with the United States. A 2003 Congressional Research Service report warned that the policy had saturated South Koreans with political rhetoric and media coverage that was breeding anti-Americanism. And this was preceded by Korea’s transformation from a poor dictatorship reliant on outsiders to a developed democracy able to stand on its own, which led to what historian Jinwung Kim called “new stirrings of nationalism.”

In his apology on Friday, Psy mentioned the U.S. military he has previously spoken out against.

“I have been honored to perform in front of American soldiers in recent months . . . and I hope they and all Americans can accept my apology.”

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